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authorThomas Bushnell <thomas@gnu.org>1997-02-25 21:28:37 +0000
committerThomas Bushnell <thomas@gnu.org>1997-02-25 21:28:37 +0000
commitf07a4c844da9f0ecae5bbee1ab94be56505f26f7 (patch)
tree12b07c7e578fc1a5f53dbfde2632408491ff2a70 /i386/util/i16/i16.h
Initial source
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diff --git a/i386/util/i16/i16.h b/i386/util/i16/i16.h
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+/*
+ * Copyright (c) 1995-1994 The University of Utah and
+ * the Computer Systems Laboratory at the University of Utah (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software is hereby
+ * granted provided that (1) source code retains these copyright, permission,
+ * and disclaimer notices, and (2) redistributions including binaries
+ * reproduce the notices in supporting documentation, and (3) all advertising
+ * materials mentioning features or use of this software display the following
+ * acknowledgement: ``This product includes software developed by the
+ * Computer Systems Laboratory at the University of Utah.''
+ *
+ * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
+ * IS" CONDITION. THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
+ * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
+ *
+ * CSL requests users of this software to return to csl-dist@cs.utah.edu any
+ * improvements that they make and grant CSL redistribution rights.
+ *
+ * Author: Bryan Ford, University of Utah CSL
+ */
+#ifndef _I386_I16_
+#define _I386_I16_
+
+#include <mach/machine/code16.h>
+
+#include "gdt.h"
+
+
+/* Macros to switch between 16-bit and 32-bit code
+ in the middle of a C function.
+ Be careful with these! */
+#define i16_switch_to_32bit() asm volatile("
+ ljmp %0,$1f
+ .code32
+ 1:
+ " : : "i" (KERNEL_CS));
+#define switch_to_16bit() asm volatile("
+ ljmp %0,$1f
+ .code16
+ 1:
+ " : : "i" (KERNEL_16_CS));
+
+
+/* From within one type of code, execute 'stmt' in the other.
+ These are safer and harder to screw up with than the above macros. */
+#define i16_do_32bit(stmt) \
+ ({ i16_switch_to_32bit(); \
+ { stmt; } \
+ switch_to_16bit(); })
+#define do_16bit(stmt) \
+ ({ switch_to_16bit(); \
+ { stmt; } \
+ i16_switch_to_32bit(); })
+
+
+#endif _I386_I16_